Immune response against FMDV induced by antigenic displayed on the surface of baculovirus and the membrane of infected insect cells

TAMI CECILIA; PERALTA ANDREA; BERISNTEIN ANALÍA; CARRILLO ELISA; PALMA EDUARDO; TABOGA OSCAR

La HaBana, Cuba

Taller; I Taller Internacional de Vaccinología Veterinaria; 2001

Antigenic site A (aa 138 to 156 of VP1) and P1 (the precursor of the four structural proteins) of FMDV serotype C3Arg85 were expressed as fusion proteins with gp64, the major surface glycoprotein from budded baculovirus AcNPV. Both chimeric FMDV-gp64 proteins were successfully expressed in the membrane of infected Sf9 cells as well as on the surface of recombinant budded baculoviruses, as revealed by Western blot experimets of sucrose gradient-fractionated supernatants and immunocytochemical stainig of infected cells. In order to evaluated the immunogenic properties of recombinant baculoviruses AcSupA and AcSupP1 (expressing gp64-site A and gp64-P1 fusion proteins, respectivaly) or infected cells, mice were inoculated with either 107 cells or 109 baculoviruses and, at different days post inoculation, serum samples were taken and the presence of specific anti-FMDV antibodies assessed by capture ELISA and seroneutralization assays. Mice inoculated with AcSupA or AcSupP1-infected cells developed a specific antibody response, even in the absence of adjuvants. Total antibody levels elicited by AcSupA-infected cells were higher than those elicited by AcSupP1-infected cells and similar to the ones obtained with inactivated FMDV-vaccinated mice used as a control. However, while antibodies induced by AcSupA-infected cells showed high seroneutralizing titers, no seroneutralizing antibodies were detected in sera from mice vaccinated with AcSupP1-infected cells. After challenge, 100% of the mice vaccinated with AcSupA-infected cells were protected, while mice vaccinated with AcSupP1-infected cells afforded 50% of protection. As expected, no portein was obtained when cells infected with baculovirus Acgp64 (overexpressing gp64) were used as immunogen in the negative control group. When recombinant baculovirus AcSupA was used as immunogen, specific antibodies against FMDV were elicited which were able to neutralize FMDV in vitro, especially when AcSupA was emulsified in incomplete freund’s adjuvants. On the contrary, AcSupP1 did not elicit specific antibodies against FMDV. At the present, challenge experiments are being carried out to determine the protective potential of these recombinant baculoviruses.